spectator sports, such as football, baseball, basketball, hockey and soccer, have become so extensively promoted as spectator sports that the team owners have been enabled to pay very lucrative salaries to the team members and team conquests, through professional leagues, have become major business activities, both in the United States and in certain foreign countries.
Each of these sports, however, suffers from various periods of boredom for spectators, even during what may be considered "action". Also, even when "action" occurs, it may be routine and unexciting. Examples would be free throws in basketball, unproductive ground plays in football, catching a fly ball in baseball, and much movement in both soccer and hockey.
In addition, action of the players is generally limited to body movements on stable surfaces, such as ground, wood floor or ice rinks, which movements may be limited by the normal physical capabilities of the players as human beings. An exception may be the sport of water polo, but actually the water in which the game is played, tends to limit quick movements of the participants.